On 11/07/2013 01:51 PM, FUJITA Tomonori wrote:
On Thu, 07 Nov 2013 13:46:36 -0800
Dan Mick <dan.mick@xxxxxxxxxxx> wrote:
I see, thanks. Using the bitmaps is simpler than the array of char if
you calculate delta and such?
I think using the array with opcode names is simpler for a human to
comparing when reading the sourcecode.
I had a bitmap of 32 bytes, one bit for each opcode, and I also
tried using an array of 256 bytes, one byte 0/1 for each opcode
but it was horrible to read from a human standpoint.
When reading the code and the bitmap/array it was very difficult to
see which opcodes were supported and which were not
by just looking at the bits.
It was also errorprone and I did several mistakes when building the
bitmap manually.
Why you built it manually? You can do something like
set_bit(WRITE_6, bitmap_addr);
?
As usual, you can steal bitmap functions from Linux kernel.
Is it worth it to mess around with bits when chars are easily
manipulated? Sure, it's 8x the data, but it's much easier to dump,
examine in debuggers, etc., and it's 256 bytes; hardly worthy of
notice.
Bitmaps are a pain in general.
Most of us (kernel people) are familar with bitmap ops rather than
functions that we would invent. That's my point.
Sure, I get that; I just mean it's not worth it for the space savings
when the usability hit is there, IMO. But it's a matter of opinion.
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